Variable stars of long period

Envelope tomography of long - period variable stars ⋆

This paper is the first one in a series devoted to the study of the dynamics of the atmospheres of longperiod variable (LPV) stars. Results from a two-monthlong monitoring of the Mira variables RTCyg and XOph around maximum light with the ELODIE spectrograph at the Haute-Provence Observatory are presented. The monitoring covers phases 0.80 to 1.16 for RTCyg and phases 0.83 to 1.04 for XOph. The...

Tomography of the atmosphere of long-period variable stars

This paper reviews the results obtained so far with the newly developed tomographic technique, which probes the velocity field across the atmosphere of long-period variable (LPV) stars. The method cross-correlates the optical spectrum with numerical masks constructed from synthetic spectra and probing layers of increasing depths. This technique reveals that the line doubling often observed in L...

The Absolute Magnitudes of Long Period Variable Stars.

Envelope tomography of long-period variable stars⋆ II. Method

A tomographic method is described that makes it possible to follow the propagation of shock waves across the photosphere of long-period variable stars. The method relies on the correlation of the observed spectrum with numerical masks probing layers of different atmospheric depths. The formation depth of spectral lines is derived from synthetic spectra of non-variable red giant stars. When appl...

The systemic velocities of four long-period cataclysmic variable stars

Although a large number of orbital periods of cataclysmic variable stars (CVs) have been measured, comparison of period and luminosity distributions with evolutionary theory is affected by strong selection effects. A test has been discovered which is independent of these selection effects and is based upon the kinematics of CVs (Kolb & Stehle, 1996). If the standard models of evolution are corr...